Method for controlling robot-assisted machining of a workpiece using a human-robot collaboration interface

Abstract

Method for controlling robot-assisted machining of a workpiece by means of an end effector within a workspace, wherein the robot controller of the robot guiding the end effector is equipped with a human-robot collaboration interface (HRC interface) for interaction between human and robot, wherein the execution of the work program by the robot is only released by the robot controller if no operator is present within the workspace, characterized in that the programming of the robot is carried out by interaction with the operator via the HRC interface within the workspace after removal and / or deactivation of the end effector and that the work program is executed without interaction with an operator if no operator is present within the workspace.

Description

[0001] The invention relates to a method for controlling robot-assisted machining of a workpiece by means of an end effector within a workspace, in which the robot controller of the robot guiding the end effector is equipped by means of a human-robot collaboration interface (HRC interface) for interaction between humans and robots, wherein the execution of the work program by the robot is only released by the robot controller when no operator is located within the workspace.

[0002] Equipping large-scale plants with manipulators or robots, especially industrial robots, is a well-known practice. For example, manipulators and robots have long been used in vehicle manufacturing for fully automated machining and assembly processes.

[0003] Although the robots known from the state of the art, especially multifunctional robots, can fundamentally perform different tasks, their functionality is generally aimed at fully automatic use.

[0004] For conventional, fully automated industrial robots, industry standards such as ISO 10218-1:2006, ISO 10218-2:2008, or Directive 2006 / 42 / EC require that the robot's work and movement area be separated from the area where people are present. In particular, the work and movement areas of the robot and the operator must remain separate at all times during operation and when the robot is in operation to prevent any hazards posed by the robot.

[0005] Furthermore, it is known to have humans interact with robots, i.e., collaborate. This type of collaboration, in which a protective zone is established within the workspace to protect humans from unwanted collisions with the robot, is referred to as human-robot collaboration (HRC). Suitable robots for this purpose are known, for example, from DE 10 2007 063 099 A1, DE 10 2007 014 023 A1, DE 10 2007 028 758 B4, DE 10 2014 216 514 B3, and US 9 043 025 B2.

[0006] WO 2007 / 096 322 A2 discloses a system for controlling the position and orientation of an object. The system comprises a measuring arrangement including a first and a second part, the first part being configured to receive forces and torques from a user, and a sensor adapted to measure forces and torques caused by changes in the position and orientation of the first part relative to the second part; and a data processing unit arranged to receive measurement data from the sensor and, based thereon, to control the position and orientation of the object. The sensor consists of a semiconductor chip with integrated sensor elements.The measuring arrangement comprises a spring arrangement mounted between the first and second parts and mechanically connected to the sensor for converting forces and torques from the user into changes in the position and orientation of the first part with respect to the second part, and the sensor is designed to measure forces and torques from the spring arrangement caused by the changes in the position and orientation of the first part.

[0007] US 2014 / 0 207 285 A1 describes a monitoring system that monitors the intrusion of an object into the environment of a robot. The monitoring system comprises a visible light irradiation section, a sensor section, and a monitoring control unit. The visible light irradiation section radiates visible light at a higher level than that of the robot onto at least one outer peripheral portion of at least one work area configured to enclose a movable area of ​​the robot and a predetermined area arranged around the work area. The sensor section monitors the entry of a new object, which is not registered in advance, into the operation area. The monitoring control unit issues a request to stop the robot to a robot controller that controls the robot when the intrusion of a new object into the work area is detected by the sensor section.

[0008] US 2010 / 0 094 461 A1 discloses a method for learning movement sequences for an industrial robot with a stand and at least one movable articulated arm. The method comprises attaching a measuring system to a measuring head at a free end of the articulated arm, attaching a handling device to an end effector at the free end of the articulated arm, operating the handling device to teach the robot the intended movement, detecting each position of the handling device via the measuring head, converting the detected positions into coordinate data, and transmitting the detected coordinate data to a monitoring and control system. The method also includes storing and evaluating the coordinate data in the monitoring and control system to develop a movement program for the robot. A suitably equipped industrial robot is also provided.

[0009] In US 2006 / 0 178 775 A1, an accelerometer is mounted on a robot to monitor the movement of a tool assembly attached to the robot end effector for safety monitoring purposes. The accelerometer provides an output signal to the robot controller, which the controller uses to monitor the robot's movement and stop that movement if predetermined values ​​for acceleration, speed, and distance are detected during the robot's passage. A handle can be attached to the robot end effector, and the accelerometer can be mounted on the handle.

[0010] In single-part production, such systems reach their limits in terms of the costs required for their implementation, system stability and process reliability.

[0011] Particularly in toolmaking, during certain manual tasks, it is often necessary to make a qualified and quick decision about how to proceed based on observations by the operators working in the respective work area.

[0012] DE 10 2009 051 146 A1 discloses a device comprising a robot with a robot controller and an associated human-robot interface, in which the detected protection zone is designed to be variable in terms of its extent and functionality depending on the robot activity and / or the robot's working position. The robot controller is accordingly expanded to include these operating modes. The various forms of interaction define the levels of temporal and spatial separation.

[0013] It is also known to assign different functionalities to a protection zone. For example, in one case, the protection zone may be assigned the function of immediately shutting down the robot, whereas in another working position, the protection zone may only be assigned the function of reducing the robot's working speed.

[0014] While the programming effort for such HRC processes makes economic sense for large-scale production processes, such robot applications have no or only very little economic benefit for individual or case-specific machining programs.

[0015] Against this background, the object of the invention is to carry out the method of the type mentioned at the outset in such a way that an advantageous use of an HRC-capable robot is also possible for small series or for individual applications.

[0016] This object is achieved by a method according to the features of patent claim 1. The subclaims relate to particularly expedient developments of the invention.

[0017] According to the invention, a method is provided in which the robot is programmed through interaction with the operator via the HRC interface within the workspace after removal and / or deactivation of the end effector, and in which the work program is executed without interaction with an operator when no operator is within the workspace. In an astonishingly simple way, the HRC interface is not used for interaction between the robot and the operator during processing, but exclusively during programming, i.e., the robot's training phase. The actual execution of the learned program then takes place without user interaction and only when no operator is within the workspace.Unlike the prior art, the HRC interface is therefore only used during the learning phase, although it has been found that the HRC interface makes programming the robot much easier. During the learning phase, the operator is located together with the robot within the workspace. In a conventional manner, the activation of the end effector is interrupted or the end effector is removed beforehand and, if necessary, replaced with a placeholder. The user then performs individual movements or virtually marks certain positions that, for example, require processing by the robot. Based on the stored processing parameters of the workpiece, programming can be carried out very quickly because the entire processing program does not have to be relearned; instead, only relevant positions are programmed - in other words, selected.

[0018] It has already proven particularly useful to deactivate the HRC interface during the execution of the work program, so that programming or any intervention in the machining program only takes place in a teach-in mode while the end effector is deactivated. This ensures that any interaction between the robot and the human is excluded when the end effector is operational.

[0019] The programming can be based on the robot controller detecting the position of a referencing element using optical sensors, so that the programming can be carried out contactlessly and without additional programming effort.

[0020] However, it is particularly practical if the robot is programmed by the operator manually guiding the robot to the desired position. This allows the operator to easily visually check the position reached. Furthermore, the movement can be performed largely intuitively, without the need to program existing restrictions as additional constraints.

[0021] Preferably, the robot is programmed by the operator marking reference points on the workpiece, so that the controller automatically completes or interpolates the movement path between the reference points. Programming a complete machining sequence is therefore unnecessary.

[0022] It has already proven particularly advantageous to program the robot by using an optical sensor to detect the operator's gestures. A control unit then identifies them and assigns them to a specific program sequence. This enables almost intuitive operation and programming, even for laypersons. Knowledge of program code is therefore unnecessary. The operator's gestures can be general or assigned to specific processing steps.

[0023] Particularly preferably, the end effector is deactivated during programming or replaced with a placeholder whose external dimensions at least largely correspond to the end effector to be used later. Such a placeholder, which, in particular, lacks cutting edges to avoid the risk of injury, also has a reduced weight and can therefore be easily guided by the operator.

Claims

[1] Method for controlling robot-assisted machining of a workpiece by means of an end effector within a workspace, in which the robot control of the robot guiding the end effector is equipped with a human-robot collaboration interface (HRC interface) for interactions between humans and robots, wherein the execution of the work program by the robot is only released by the robot control when no operator is within the workspace, characterized by that the programming of the robot is carried out by interaction with the operator via the HRC interface within the workspace after removal and / or deactivation of the end effector and that the work program is executed without interaction with an operator if no operator is within the workspace. [2] Method according to claim 1, characterized bythat the HRC interface is deactivated during the execution of the work program. [3] Method according to claims 1 or 2, characterized by that the robot is programmed by the operator manually guiding the robot. [4] Method according to at least one of the preceding claims, characterized by that the robot is programmed by the operator marking reference points on the workpiece. [5] Method according to claim 4, characterized by that the marking is detected by an optical sensor and an image evaluation is carried out in a control unit. [6] Method according to at least one of the preceding claims, characterized by that the robot is programmed by using an optical sensor to detect the operator's gestures, which are then identified by a control unit and assigned to a specific program sequence. [7] Method according to at least one of the preceding claims, characterized by that the end effector is deactivated during programming. [8] Method according to at least one of the preceding claims, characterized by that the end effector is replaced by a placeholder during programming. [9] Method according to at least one of the preceding claims, characterized by that a movement path between different positions on the workpiece to be machined is interpolated by means of the control.